Functionalized periodic mesoporous organosilicas: Hierarchical and chiral materials

The integration of organic and inorganic fragments within the pore walls of the periodic mesoporous organosilicas (PMOs) represents one of the recent breakthroughs in material science. The resulting PMOs are promising materials for applications in such areas as catalysis, adsorption, separation and drug-delivery. We summarize here the recent progress made in the synthesis of PMOs with hierarchical structures and large functional groups, with special emphasis on the chiral mesoporous organosilicas and their potential applications as novel chiral solids in heterogeneous asymmetric catalysis.

A smart dual-responsive nanoplatform for delivery of prochloraz for the control of rice blast disease

Nano-controlled release formulations present a promising strategy to mitigate pesticide losses and enhance efficiency.In this study,a pH and GSH-responsive nanoplatform using mesoporous organosilica nanoparticles(MONs)as a carrier and poly(tannic acid)(PTA)as capping agent was established for controlling prochloraz(Pro)release.The obtained Pro@MON@PTA was characterized by transmission electron microscopy(TEM),scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA).The results indicate the successful preparation of Pro@MON@PTA nanoparticles,featuring uniform particle size(190 nm),excellent dispersibility,and a prochloraz loading efficiency of 17.2%.Evaluation of contact angle and adhesion work demonstrated superior adhesion of MON@PTA to rice leaves compared to MON.Controlled release studies revealed dual-responsive release properties of Pro@MON@PTA to acid and GSH.Additionally,photostability testing indicated effective ultraviolet light shielding by the carrier,reducing prochloraz degradation under irradiation.Bioassay results indicated equivalent fungicidal activity against Magnaporthe oryzae between Pro@MON@PTA and prochloraz technical and prochloraz EW after a 7-day treatment.However,in vivo experiments demonstrated that Pro@MON@PTA exhibited superior control efficacy compared to prochloraz EW.These findings suggested that MON@PTA holds significant potential for plant disease management.

Advances in microwave assisted synthesis of ordered mesoporous materials

Mesoporous materials with uniform pores and high specific areas are used in many fields including catalysts, separation and adsorbents, etc. In order to find faster and more economical synthesis routes, the use of microwave heating was deeply studied. Compared to the hydrothermal method, microwave energy can heat the samples to crystallization temperature rapidly and uniformly result in homogeneous nucleation and shorten crystallization time. The basic principles of microwave assisted synthesis and advantages of microwave heating, and the obtained progress concerning ordered mesoporous materials through microwave synthesis were summarized.

Fabrication of Pd-Nb bimetallic doped organosilica membranes by different metal doping routes for H_(2)/CO_(2) separation

Monometallic doping has proved its superiority in improving either permselectivity or H_(2) permeability of organosilica membranes for H_(2)/CO_(2) separation,but it is still challenging to break the trade-off effect.Herein,we report a series of Pd-Nb bimetallic doped 1,2-bis(triethoxysilyl)ethane(Pd-Nb-BTESE,PNB)membranes with different metal doping routes for simultaneously improving H_(2) permeance and H_(2)/CO_(2) permselectivity by the synergetic effects of Pd and Nb.The doped Pd can exist in the BTESE network as nanoparticles while the doped Nb is incorporated into BTESE network forming Nb-O-Si covalent bonds.The metal doping routes significantly influence the microstructure of PNB networks and gas separation performance of the PNB membranes.We found that the PNB membrane with Pd doping priority(PNB-Pd)exhibited the highest surface area and pore volume,comparing with Nb doping priority(PNB-Nb)or Pd-Nb simultaneous doping(PNB-PdNb).The PNB-Pd membrane could not only exhibit an excellent H_(2) permeance of~10^(−6) mol·m^(−2)·s^(−1)·Pa^(−1) but also a high H_(2)/CO_(2) permselectivity of 17.2.Our findings may provide novel insights into preparation of bimetallic doped organosilica membranes with excellent H_(2)/CO_(2) separation performance.

Controlling pore structures of Pd-doped organosilica membranes by calcination atmosphere for gas separation

Pd-doped organosilica membranes were prepared by controlling calcination atmospheres(i.e.POS-Air,POS-N2,POS-H2,POS-H2/N2)to tailor their networks for improving their gas separation performance.This study shows that Pd(Ⅱ)could be only maintained under non-reductive calcination atmosphere,while inert and reducing calcination atmosphere is more beneficial to maintain organosilica moieties in POS networks.POS-H2/N2 membrane showed the optimal H2 separation performance that its permselectivities for H2/CO2,H2/N2,H2/CH4 and H2/SF6 are 15.0,96.7,173.0 and 3400.0,re spectively.Moreover,it is found that H2 molecules pass through the four membranes based on activated diffusion,while CO2 molecules permeation through POS-N2 and POS-Air membrane is dominated by surface diffusion.This work may provide insight into the understanding of the calcination atmosphere effect on gas separation performance of metal-doped organosilica membranes.

Tuning sol size to optimize organosilica membranes for gas separation

A series of organosilica sols are prepared by the polymeric sol–gel method using 1,2-bis(triethoxysilyl)ethane(BTESE)as the precursor.Particle size distributions of the BTESE-derived sols are systematically investigated by carefully adjusting the synthesis parameters(i.e.,water ratios,acid ratios and solvent ratios)in the sol process.In certain conditions,increasing the water ratio or the acid ratio tends to cause larger sol sizes and bimodal particle size distributions.However,higher solvent ratios lead to smaller sol sizes and unimodal particle size distributions.The organosilica membranes prepared from the optimized sols show excellent H_2 permeances(up to 4.2×10^(-7)mol·m^(-2)·s^(-1)·Pa^(-1))and gas permselectitivies(H_2/CO_2 is 9.5,H_2/N_2 is 50 and H_2/CH_4 is 68).This study offers significant insights into the relationship between the sol synthesis parameters,sol sizes and membrane performance.

Soft Mesoporous Organosilica Nanoplatforms Improve Blood Circulation,Tumor Accumulation/Penetration,and Photodynamic Efficacy

To date,the ability of nanoplatforms to achieve excellent therapeutic responses is hindered by short blood circulation and limited tumor accumulation/penetration.Herein,a soft mesoporous organosilica nanoplatform modified with hyaluronic acid and cyanine 5.5 are prepared,denoted SMONs-HA-Cy5.5,and comparative studies between SMONs-HA-Cy5.5(24.2 MPa)and stiff counterparts(79.2 MPa)are conducted.Results indicate that,apart from exhibiting a twofold increase in tumor cellular uptake,the soft nanoplatforms also display a remarkable pharmacokinetic advantage,resulting in considerably improved tumor accumulation.Moreover,SMONs-HA-Cy5.5 exhibits a significantly higher tumor penetration,achieving 30-μm deeper tissue permeability in multicellular spheroids relative to the stiff counterparts.Results further reveal that the soft nanoplatforms have an easier extravasation from the tumor vessels,diffuse farther in the dense extracellular matrix,and reach deeper tumor tissues compared to the stiff ones.Specifically,the soft nanoplatforms generate a 16-fold improvement(43 vs.2.72μm)in diffusion distance in tumor parenchyma.Based on the significantly improved blood circulation and tumor accumulation/penetration,a soft therapeutic nanoplatform is constructed by loading photosensitizer chlorin e6 in SMONs-HA-Cy5.5.The resulting nanoplatform exhibits considerably higher therapeutic efficacy on tumors compared to the stiff ones.

Aminopropyl-containing ionic liquid based organosilica as a novel and efficient adsorbent for removal of crystal violet from wastewaters

Herein a novel aminopropyl-containing ionic liquid based organosilica(ILOS-NH_2) is prepared, characterized and applied as effective adsorbent for removal of crystal violet(CV) dye from wastewater. The ILOS-NH2 material was synthesized by hydrolysis and co-condensation of 1,3-bis-(3-trimethoxysilylpropyl)-imidazolium chloride(BTMSPIC) under acidic conditions followed by treatment with 3-aminopropyl-trimethoxysilane in toluene under reflux conditions. This material was characterized using scanning electron microscopy(SEM), diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS), thermal gravimetric analysis(TGA) and energy dispersive X-ray analysis(EDAX). The material was effectively used in the removal of crystal violet at ambient temperature and showed high capacity and stability under applied conditions. The efficacy of p H, contact time, adsorbent dose, initial dye concentration, temperature, and isotherm studies and the applicability of pseudo-first, second order and Elovich kinetic models have also been investigated.

Growth of CeCo-MOF in dendritic mesoporous organosilica as highly efficient antioxidant for enhanced thermal stability of silicone rubber

High-efficient rubber antioxidants for enhanced heat resistance without compromising mechanical properties remain an enormous and long-term challenge for the rubber industry.Herein,we employed the in-situ growth of Ce-doped Co-metal-organic framework(Ce Co-MOF)in dendritic mesoporous organosilica nanoparticles(DMONs@Ce Co-MOF,denoted as DCCM)to prepare a novel antioxidant that exhibit outstanding thermal stability.Dendritic mesoporous organosilica nanoparticles(DMONs)effectively alleviated the incompatibility of Ce Co-MOF in the polymer matrix,and the effective scavenging of free radicals was attributed to the various oxidation states of metal ions in Ce Co-MOF.Surprising,by adding only0.5 phr(parts per hundred of rubber)of DMONs@Ce Co-MOF to silicone rubber,(SR),the retention rate of tensile strength increased from 37.3%to 61.6%after aging 72 h at 250℃,and the retention rate of elongation at break of DCCM/SR1 composites reached 68%,which was 5.43 times of SR.The strategy of anchoring MOFs on the surface of silica also provides a viable method for preparing effective compound functionalized rubber antioxidant.

Dendrimer-induced synthesis of porous organosilica capsules for enzyme encapsulation

Organic matter-induced mineralization is a green and versatile method for synthesizing hybrid nanostructured materials,where the material properties are mainly influenced by the species of natural biomolecules,linear synthetic polymer,or small molecules,limiting their diversity.Herein,we adopted dendrimer poly(amidoamine)(PAMAM)as the inducer to synthesize organosilica-PAMAM network(OSPN)capsules for mannose isomerase(MIase)encapsulation based on a hard-templating method.The structure of OSPN capsules can be precisely regulated by adjusting the molecular weight and concentration of PAMAM,thereby demonstrating a substantial impact on the kinetic behavior of the MIase@OSPN system.The MIase@OSPN system was used for catalytic production of mannose from Dfructose.A mannose yield of 22.24% was obtained,which is higher than that of MIase in organosilica network capsules and similar to that of the free enzyme.The overall catalytic efficiency(kcat/Km)of the MIase@OSPN system for the substrate D-fructose was up to 0.556 s^(-1)·mmol^(-1)·L.Meanwhile,the MIase@OSPN system showed excellent stability and recyclability,maintaining more than 50% of the yield even after 12 cycles.

Amphipathicity mediated endocytosis of mesoporous silica nanoparticles with tunable frameworks

Due to the amphiphilic nature of phospholipids in the cell membrane,the amphipathicity of the nanomedicine plays a crucial role in the endocytosis.However,limited biological characterization methods restrict the study of the state of nanoparticles with different amphiphilicities on cell membranes.The understanding of interaction of amphiphilic particle with cell membrane is still lacking.Herein,by combining the dissipative particle dynamics(DPD)with the framework construction of mesoporous silica nanoparticles(MSNs),we demonstrate the enhanced endocytosis induced by the hydrophobicity.DPD results confirm that the presence of hydrophobic groups on the surface of nanoparticles can disturb the integrity of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine(POPC)membrane and induce activation of phospholipids to a higher energy level,thereby facilitating the wrapping of nanoparticles.To validate the simulation findings,uniform MSNs with hydrophilic pure silica framework and two types of amphiphilic MSNs with varying hydrophilic organic groups in the framework are rationally synthesized by using different silane precursors.The obtained three kinds of MSNs show similar diameter(~100 nm)and mesopores(~2 nm),but distinct hydrophobicity/hydrophilicity ratio.The phenyl-bridged MSN with a carbon content of 27.1%exhibits enhanced cellular uptake,consistent with the theoretical simulation results.This work sheds light on how the surface amphipathicity influences endocytosis through the interaction with cell membrane.

Remarkable enhancement of gas selectivity on organosilica hybrid membranes using urea-modulated metal-organic framework nanoparticles

Metal-organic framework/organosilica hybrid membranes on tubular ceramic substrates have shown great potential for the implementation of membrane technology in practical gas separation projects due to their higher permeance compared to commercial polymers.However,the selectivities of the reported membranes are moderate.Here,we have incorporated urea-modulated metal-organic frameworks into organosilica membranes to greatly enhance its separation performance.The urea-modulated metal-organic frameworks exhibit less-defined edges of crystallographic facets and high defect density.They can be well-dispersed in the organosilica layer,which substantially suppresses the interfacial defects between metal-organic frameworks and organosilica,which is beneficial for improving the selectivity of membranes for gas separation.The results have shown that the enhanced ideal selectivity of H_(2)/CH_(4) was 165 and that of CO_(2)/CH_(4) was 43,with H_(2) permeance of about 1.25×10^(−6) mol·m^(−2)·s^(−1)·Pa^(−1) and CO_(2) permeance of 3.27×10^(−7) mol·m^(−2)·s^(−1)·Pa^(−1) at 0.2 MPa and 25℃.In conclusion,the high level of hybrid membranes can be used to separate H_(2)(or CO_(2))from the binary gas mixture H_(2)/CH_(4)(or CO_(2)/CH_(4)),which is important for gas separation in practical applications.Moreover,the simple and feasible modulation of metal-organic framework is a promising strategy to tune different metal-organic frameworks for membranes according to the actual demands.

Magnetic wrinkled organosilica-based metal-enzyme integrated catalysts for enhanced chemoenzymatic catalysis

Core-shell structured magnetic wrinkled organosilica-based metal-enzyme integrated catalysts were synthesized,and their catalytic performances were studied in the chemoenzymatic dynamic kinetic resolution of chiral amines in an organic solvent,as well as in the chemoenzymatic synthesis of chiral alcohols in water.Structureperformance studies revealed the important influence of their tunable structure and composition on the optimization of activity,stability,and recyclability in chemoenzymatic catalysis.

“Pincer movement”:Reversing cisplatin resistance based on simultaneous glutathione depletion and glutathione S-transferases inhibition by redox-responsive degradable organosilica hybrid nanoparticles

The therapeutic efficacy of cisplatin has been restricted by drug resistance of cancers.Intracellular glutathione(GSH)detoxification of cisplatin under the catalysis of glutathione S-transferases(GST)plays important roles in the development of cisplatin resistance.Herein,a strategy of“pincer movement”based on simultaneous GSH depletion and GST inhibition is proposed to enhance cisplatin-based chemotherapy.Specifically,a redox-responsive nanomedicine based on disulfide-bridged degradable organosilica hybrid nanoparticles is developed and loaded with cisplatin and ethacrynic acid(EA),a GST inhibitor.Responding to high level of intracellular GSH,the hybrid nanoparticles can be gradually degraded due to the break of disulfide bonds,which further promotes drug release.Meanwhile,the disulfide-mediated GSH depletion and EA-induced GST inhibition cooperatively prevent cellular detoxification of cisplatin and reverse drug resistance.Moreover,the nanomedicine is integrated into microneedles for intralesional drug delivery against cisplatin-resistant melanoma.The in vivo results show that the nanomedicine-loaded microneedles can achieve significant GSH depletion,GST inhibition,and consequent tumor growth suppression.Overall,this research provides a promising strategy for the construction of new-type nanomedicines to overcome cisplatin resistance,which extends the biomedical application of organosilica hybrid nanomaterials and enables more efficient chemotherapy against drug-resistant cancers.

A facile ＂ship-in-a-bottle＂ approach to construct nanorattles based on upconverting lanthanide-doped fluorides

Rattle structure is a topic of great interest in design and application of nano- materials due to the unique core@void@shell architecture and the integration of functions. Herein, we developed a novel ＂ship-in-a-bottle＂ method to fabricate upconverting （UC） luminescent nanorattles by incorporating lanthanide-doped fluorides into hollow mesoporous silica. The size of nanorattles and the filling amount of fluorides can be well controlled. In addition, the modification of silica shell （with phenylene and amine groups） and the variation of efficient UC fluorides （NaYF4：Yb, Er, NaLuF4：Yb, Er, NaGdF4：Yb, Er and LiYF4：Yb, Er） were readily achieved. The resulting nanorattles exhibited a high capacity and pH-dependent release of the anti-cancer drug doxorubicin （DOX）. Furthermore, we employed these nanorattles in proof-of-concept UC-monitoring drug release by utilizing the energy transfer process from UC fluorides to DOX, thus revealing the great potential of the nanorattles as efficient cancer theranostic agent.

Generic synthesis and versatile applications of molecularly organic-inorganic hybrid mesoporous organosilica nanoparticles with asymmetric Janus topologies and structures

Precise control over the morphology,nanostructure,composition,and particle size of molecularly organic-inorganic hybrid mesoporous organosilica nanoparticles （MONs） still remains a major challenge,which severely restricts their broad applications.In this work an efficient bridged organic group-determined growth strategy has been proposed for the facile synthesis of highly dispersed and uniform MONs with multifarious Janus morphologies,nanostructures,organic-inorganic hybrid compositions,and particle sizes,which can be easily controlled simply by varying the bridged organic groups and the concentration of bis-silylated organosilica precursors used in the synthesis.In addition,the formation mechanism of Janus MONs determined by the bridged organic group has been discussed.Based on the specific structures,compositions,and asymmetric morphologies,all the synthesized Janus MONs with hollow structures （JHMONs） demonstrate excellent performances in nanomedicine as desirable drug carriers with high drug-loading efficiencies/capacities,pH-responsive drug releasing,and enhanced therapeutic efficiencies,as attractive contrastenhanced contrast agents for ultrasound imaging,and as excellent bilirubin adsorbents with noticeably high adsorption capacities and high blood compatibilities.The developed versatile synthetic strategy and the obtained JHMONs are extremely important in the development and applications of MONs,particularly in the areas of nanoscience and nanotechnology.

The effect of solvent in evaporation-induced self-assembly:A case study of benzene periodic mesoporous organosilica

Volatile organic solvents were considered to have little influence on the synthesis of mesostructured materials through evaporation-induced self-assembly(EISA),because upon evaporation they leave the sol and hence do not interfere with the self-assembly process.We show here that the choice of solvent is crucial in the synthesis of thin films of phenylene-bridged periodic mesoporous organosilica(benzene PMO).Methanol is found to be a better solvent for the synthesis of thin films,whereas ethanol favors the formation of(HO)3Si-C6H4-Si(OH)3 crystals,the identity and structure of which is established by X-ray diffraction.A ternary reactant composition diagram is designed to visualize the relationship among multiple synthesis experiments and to guide the interpretation of experimental results and optimization of the quality of the periodic mesoporous organosilica film.Our study highlights the importance of solvent choice,a factor often neglected in EISA.We expect it to inspire researchers to explore the effect of solvent in designing the synthesis of mesoporous materials.

Controlled PEGylation of periodic mesoporous organosilica nanospheres for improving their stability in physiological solutions

The stability of periodic mesoporous organosilica(PMO) nanoparticles in physiological solutions greatly affects their potential biomedical applications. Herein, thioether-bridged PMO nanospheres with a diameter of 61 nm are synthesized. Then, the thioether-bridged PMO nanospheres are modified with different molecular weighted polyethylene glycol(PEG) via click reaction for the first time. FI-IR and thermogravimetric analysis confirm the successful modification of PEG on the PMO. The influence of PEG molecular weight on the dispersity and stability of the PMO-PEG in phosphate buffer(PBS) and Dulbecco's modified Eagle's medium(DMEM) is studied. The results show that the PEG coating increases the stability and dispersity of PMO in the biological solutions. The PMO-PEG1K, PMO-PEG2K, and PMOPEG5K have better stability in PBS solution. The PMO-PEG2K shows best stability and dispersity in DMEM. Over all, this work provides important method and knowledge to guide the modification of PMO for biomedical

Deformable double-shelled hollow mesoporous organosilica nanocapsules:A multi-interfacial etching strategy

Multishelled hollow structures have drawn increasing interest because of their peculiar compartmentation environments and physicochemical properties.In this work,deformable double-shelled hollow mesoporous o rganosilica nanocapsules(DDHMONs)were succes s fully synthesized by a multi-interfacial etching strategy.The obtained DDHMONs have a double-shelled structure with aninorganic-organic hybrid framework,a uniform outer layer(~320 nm)and inner layer(~180 nm),ordered mesochannels(~2.21 nm),and a large specific surface area(~1233 m^(2)/g).In vitro toxicity tests show that the DDHMONs have excellent biocompatibility when coincubated with human breast cancer cells.In addition,the anti cancer substance doxorubicin(DOX)can be highly loaded in DDHMONs(~335μg/mg).The results from flow cytometry together with confocal laser scanning microscopy show that DOX can be efficiently delivered into MCF-7 cells by DDHMONs,thus improving chemotherapeutic efficiency and demonstrating that DDHMONs have potential nanomedicine applications as anticancer agents.